About this item LARGE QUANTITY – 28-pack of 4 1/2 inch 120 grit flap discs. Satisfying all your blending, sanding and finishing requirements. Perfectly meets all your needs. EXTREME DURABILITY AND VALUE – The flap sanding discs are made of TOP-LEVEL hard zirconia alumina material, which lasts longer than standard aluminum oxide abrasive material, built for a more robust and economical grinding wheel. FLAP DISCS WITH FIBERGLASS BACKING PLATE - Grinder sanding discs have long-lasting use. A safe and effective product made with durable Material. It’s fast polishing, and it has durable fiberglass backing and fine crystal size. The flap discs are made with a fiberglass backing plate that effectively absorbs vibrations without smear during usage, bringing more stable and efficient grinding. MEET ALL YOUR NEEDS – This flap disc is used for all kinds of projects, ranging from metal and woodworking, concrete grinding and finishing, stone smoothing and finishing, to rust removal. It perfectly grinds anything you need for your projects. BEST MATCH SIZE – Each angle grinder sanding disc measures at 4-1/2-inch diameter with a 7/8-inch arbor size, making it compatible with grinders operating up to 13, 300 RPM.